This XHTML Basic 1.0 document is being sent with a Content-Type of text/html.
You can try loading this page with these MIME content types:
You should not see a <?xml version="1.0"?> tag above. HTML 2.0 compatible browsers will not render this tag as body text.
The registered content type for XHTML is application/xhtml+xml. The +xml suffix is standard for XML based media types by RFC 3023: XML Media Types.